(a) Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and, more particularly, to a transflective liquid crystal display device.
(b) Description of the Related Art
Generally, an LCD device includes a pair of panels each having field generating electrodes disposed on their inner surfaces, and a dielectric anisotropy liquid crystal layer interposed between the pair of panels. In the LCD device, a variation of a voltage difference between the field generating electrodes, i.e., a variation in strength of an electric field generated by the field generating electrodes changes a transmittance of light passing through the LCD device, and thus images are obtained by controlling the voltage difference between the field generating electrodes.
The LCD device utilizes artificial light emitted by lamps of a backlight unit separately provided, or ambient light as a light source because the LCD device is a light-receiving device incapable of self-emitting. In the LCD device, the artificial light emitted by the lamps of the backlight unit or the ambient light passes through the liquid crystal layer only once, or twice by reflection. An LCD device using the artificial light emitted by the lamps is called a “transmissive” type of LCD device and an LCD device using the ambient light is called a “reflective” type of LCD device. The reflective type LCD devices are commonly used in medium and small size display devices. Another type of LCD device is a “transflective” or “reflective-transmissive” LCD device capable of selectively using light from the backlight unit and ambient light in response to current circumstances. The transflective LCD device is commonly used in medium and small size display devices.
In the transflective LCD device, since each pixel has a transmissive area where light passes through the liquid crystal layer only once, and a reflective area where light passes through the liquid crystal layer twice, a thickness of the liquid crystal layer disposed in the transmissive area, i.e., a cell gap of the transmissive area, is formed differently from a cell gap of the reflective area. The transflective LCD device may be driven with different voltages in a transmissive mode than in a reflective mode. In the transmissive mode, the transflective LCD device mainly uses the transmissive area, and in the reflective mode, the transflective LCD device mainly uses the reflective areas
Meanwhile, LCD devices have a drawback in that a standard viewing angle, based on a contrast ratio above a predetermined level, is not very wide. A narrow standard viewing angle has been relatively unimportant since transflective LCD devices had been commonly used in the medium and small size display devices as mentioned above. However, recently, as the medium and small size display devices are used for a greater variety of purposes, demands for a wide viewing angle of transflective LCD devices are increasing.
Various methods have been proposed to enlarge the standard viewing angle of LCD devices. A widely used method is to align the liquid crystal layer vertically with respect to the pair of panels and to form apertures in or projections on the field generating electrodes. Another method is to control tilt directions of liquid crystal molecules of the liquid crystal layer in various manners when an electric field is generated in the liquid crystal layer.
However, when the above-described methods are applied to the transflective LCD device commonly used in the medium and small size display devices, an additional process is required to form the apertures in the field generating electrodes. Further, it is not so easy to form the apertures in pixels accurately because the pixels are very small.